The invention herein resides in the art of packaging equipment and, more particularly, to a device employed for checking the contents of packages by weight. Specifically, the invention relates to a rotary drum positioned beneath the conveyor of a bag packaging system and adapted to receive individual bags, check the weight of the bag and its contents, and by controlling the direction of rotation of the drum, either accept or reject the bag based upon comparison of the weight to a set criteria.
The use of bagging machines is now widely accepted as a method for depositing a volume of parts or other materials into a bag for ultimate sale or subsequent combination with subassemblies for final packaging. It is well known that nuts, bolts, screws, cotter pins, caps, and the like are often packaged in bags by the use of bagging machines for such ultimate use or distribution. Typically, such bags are filled with a state of the art bagging machine which is generally programmed to deposit specified numbers of various pieces into the bags. While bagging equipment is generally quite accurate, errors in the count do occur and, accordingly, it is necessary to provide a device for checking the contents of the bag as a means of quality control. For this purpose, various types of scales or weight checkers have been devised for determining, by weight, the likelihood of a bag having the appropriate number or combination of parts therein. In general, such check weighers have an associated window of acceptable weight and, if a bag is found to fall within that window, it is accepted. Such check weighers are generally known and widely used.
The prior art check weigher has typically allowed a conveyor of the bagging system or bagger to drop on a top plate of a scale across which a pair of orthogonally positioned reciprocating push plates are positioned. If the weight of the bag and its contents falls within the acceptable window, one of the push plates is extended across the scale and pushes the bag in a first direction where it is received in a bin for acceptable bags. The push plate is then retracted. In the event the bag and its contents falls outside the window, the other orthogonally positioned push plate is extended to push the bag and its contents into a second bin for unacceptable bags. That plate is then similarly retracted. While such prior art check weighers have generally been acceptable in implementation, it has been found that their operation is unnecessarily slow, so the accept/reject push plates, which are typically actuated by solenoids or air cylinders, must necessarily pass through a complete reciprocating cycle in order to effect the accept/reject operation. In other words, each push plate must both extend and retract before a subsequent bag of materials can be placed upon the surface of the scale plate. Often, the check weigher is the slowest operating mechanism in the total bagging system and, accordingly, the required dual action of prior art check weighers has unnecessarily impeded the operation of otherwise high speed bagging systems.
There is a need in the art for a check weigher which requires a single action to accept or reject a bag of materials and, upon such acceptance or rejection, is immediately available for receipt of a subsequent bag.
In light of the foregoing, it is a first aspect of the invention to provide a check weigher for bagging systems in which the actuating mechanism moves in only one direction during an accept or reject cycle.
Another aspect of the invention is the provision of a check weigher for bagging systems which is ready for receipt of another bag immediately upon depositing a prior bag of materials into an accept or reject bin.
Still another aspect of the invention is the provision of a check weigher for bagging systems which eliminates the need for a pair of orthogonally positioned push plates for the accept/reject operation.
Yet another aspect of the invention is the provision of a check weigher for bagging systems which is easy to operate and control, which can be readily constructed with state of the art apparatus and techniques, and which is given to ease of implementation with presently existing bagging systems.
The foregoing and other aspects of the invention which will become apparent as the detailed description proceeds are achieved by a rotary weighing system, comprising: a conveyor transporting bags of parts; and a compartmentalized drum positioned beneath said conveyor to receive bags dropped therefrom.
Other aspects of the invention which will become apparent herein are attained by a method for accepting and rejecting bags of materials based on weight, comprising: dropping of a bag of materials into a rotatable drum; determining the weight of the bag of materials received by the rotatable drum; selectively rotating the drum in a direction determined by the weight of the bag of materials; and receiving said bag of materials in a first area when the drum is rotated in a first direction and in a second area when said drum is rotated in a second direction.